Method of treating rods and wire



May 24, 1938. R. E. CRAMER 2,118,158

METHOD OF TREATING RODS AND WIRE 7 Filed April 18, 1950 2 Sheets-Sheet 1N fiwezzi'or:

' 05587 5 CEHMEE,

if I W ,4

May 24-, 1938. I R E ER 2,118,168

METHOD OF TREATING RODS AND WIRE Filed April 18, 1950 2 Sheets-Sheet-Zjme'ntor:

505557 E. CEHMEE,

Patented May 24, 1938 UNITED STATES PATEN oer-Ice 2,118,168 a METHOD orTREATING aons AND wmn Robert E. Cramer, Pittsburgh, Pa. ApplicationApril is, 1930, Serial No. 445,411

5 Claims. (01. 14H) This invention relates to a method of treating rodsand'wire and more particularly to a novel method of baking previouslypickled or cleaned and lime-coated rods to remove occluded 5 hydrogenand to dry the lime coating, and has for its object the provision of anovel method whereby the baking may be done under controlled conditionswith high temperatures so as to quickly and completely remove all theoccluded hydrogen and 10 dry the lime coating.

Wire is drawn in 'a cold state from previously prepared raw material,known as rods, which are produced by hot rolling. The hot rolled rodshave a scaled surface which prevents successful 15 cold drawing. Thisscale, therefore, must be removed and is commercially done by a cleaningstep known as pickling. Commercial pickling is practiced by immersingthe rods in a hot solution or bath of water and acid. After the rods 20are pickled, the rods are dipped or immersed in a lime solution or bathto form a lime coatin which prevents rusting, neutralizes the acid, andserves as a lubricant and protective coating in the subsequent colddrawing operations.

The cleaning or pickling and lime coating of the rods is necessary tosuccessful wire production, but these operations, however, introduce twofactors which are detrimental to the wire drawing operation and whichmust be removed 30 before the wire can be drawn.

The two factors detrimental are occluded hydrogen in the rods, known inthe art, as acid brittleness and the wet lime coating which must bethoroughly dried.

When the steel rods are pickled in an acid solution, a part of thehydrogen from the acid is absorbed into the surface of the steel. To theindustry this phenomenon is known as occluded v hydrogen or acidbrittleness, the latter term 10 resulting from the fact that rods orwire which have not had the hydrogen removed are so brittle that theywill break whenv an attempt is made to draw them.

The occluded hydrogen is removed and the lime coating dried in a singleoperation known as baking. i Heretofore, the baking operation hasgenerally been carried out in a more or less haphazard way in ovens orchambers heated indirectly by the burning of fuel and the passage of theproducts of combustion through sub-floor and overhead flues, the heatbeing radiated into the'oven from the flue walls. Variations of the fluearrangements have been used but in every instance the heating I severaltrucks loadedwith rods or IIw-II of Figure 1. 1 the baker or oven as awhole is composed of end is done by radiation and no attempt has beenmade to circulate the air in the oven or baker. Ovens or bakersconstructed and operated as above have varyingftemperatures at differentpoints, since the. zones closest to the flues or di- 5 rectly over thefiring pitsv aregenerally hottest, 1 the stagnant atmosphere hinders thedrying operation, and it-.is-not unusual to find variations of from 150degrees to 200 degrees Fahrenheit in the temperature of different partsof the same oven Other factors are also present in the prior art bakersto cause non-uniform temperatures, such as lime dust on the floor actingas an insulator, physical condition-of the fines causing hot spots, etc.Y

Imperfect baking is obviously inherent in the type of baker abovedescribed. The operator must depend on his experience or memory of how asection of thebaker functioned on the preceding batch. There are so manyvariables present which are uncontrollable by commercial methods as tolead to the characterization of this type of baker as hit or miss" andhaphazard.

'Itis not uncommon for operators to be compelled to rebake materialwhich has failed to work in the wire drawing operations.

All of the above objectionable features are overcome by the presentmethod. The time necessary to bake or dry the rods is materiallyreduced, and all the rods in the oven or baker are subjected to auniform temperature and volume of circulating air so that the wholechore is uniformly treated, resulting in a uniform product completelyfreed of occluded hydrogen and perfectly dry.

The present method consists broadly in providing an oven chamber orcompartment to receive v wire, and hav ing a steam coil or other heatingelement and a 1 fan arranged to recirculate the air from the ovenchamber over the heating element and through the chamber. After the rodsor wire are positioned in the oven chamber the fan is started to forcethe continued recirculation of the oven air over theheating element,thus filling the whole oven chamber with high temperature circulatingair. causing a uniform temperature throughout the chamber and thoroughlybaking and drying the rods or wire in a minimum oftime,

In the drawings: 7 Figure 1 is a plan view partly in section showing afurnacoconstructed to carry out this method. Figure 2 is a sectionalview taken on the line Referring more particularly to the drawings,

' the forward end thereof,

walls 2 and 3 and top wall 4 which may be of brick or other usualconstruction with or without a layer of insulating material 5, asdesired. The back and front of the oven chamber are closed by doors 6which are slidably mounted in guideways 1' for vertical movement topermit the charging and discharging of buggies loaded with material tobe baked.

The baker is divided from front to back into sub-oven chambers A bywalls B, and each suboven chamber is provided with tracks 8 on which theloaded buggies of material are propelled.

Each of the sub-oven chambers is provided with a heating unit D mountedon top of the chamber and composed of a casing l divided by a wall 92into a heating chamber 83 and a fan chamber M. The wall I2 is spacedfrom the bottom of the casing 50 to provide a port l between thechambers 53 and M. A steam coil is or other source of heat is mounted inthe chamber is and a fan H is mounted in the chamber M. A hot airdelivery conduit l8 communicates with the fan chamber it and extendsdownwardly through the top wall of the chamber adjacent and an airreturn conduit l9 communicates with the heating chamber I3 and extendsdown into the sub-chamber and along the underside of the top wall of thesubchamber to a. point adjacent the rear end of the chamber.

In operation, the fan I! will cause a continued recirculation of theatmosphere in the subchamber over the steam coil l6 so as to maintain acirculation of constant temperature air in said chamber.

Due to the constant circulation of the chamber air over the steam coilIS the temperature of the chamber atmosphere will be uniform throughout,and the temperature is definitely fixed by the steam pressure applied tothe coil. Various temperatures are possible for different classes orgrades of steel and can be predetermined and maintained, as desired,merely by regulation of the steam pressure. Advantage is taken of thephysical characteristics of steam which has a definite temperature foreach pressure. Advantage is also taken of the fact that steam remainsat'constant temperature while giving up its heat. The rapid circulationof the same air over and over the steam coils quickly brings the airtemperature up to that very closely approximating the steam temperature,and the forced circulation insures the sametemperature at all points inthe chamber.

The above conditions being assured, it will readily be seen that theremoval of occluded hydrogen is brought to the highest state ofperfection, with the resulting assurance of the desired quality ofproduct.

Exact control of each oven compartment or sub-chamber is possible bysimple regulation of the steam pressure and fan speed of the heatingunit of the respective sub-chambers.

The wet line coating on the rods is dried in a minimum of time due tothe rapid circulation of the air, which is preferably heated totemperatures above 212 degrees Fahrenheit, at which lation to heat saidair temperature it will absorb an infinite amount 1 of moisture.

The heat transferred from the air to the material is accelerated becauseof the circulation of the air. Therefore, the material reaches the de-vsired temperature quicker than ina stagnant atmosphere and the removalof hydrogen is accelerated as well as uniformly removed.

By accelerating the hydrogen removal and lime-drying the capacity of theapparatus is greatly increased and, therefore, fewer ovens or bakers arenecessary for a given output.

It will be understood that while I have shown and described a certainspecific embodiment of apparatus for carrying out my novel method, thati do not wish to be limited thereto, since various modifications of theapparatus may be made for carrying out the method.

It claim:

1. The method of treating rods and wire to remove brittleness caused byoccluded hydrogen which consists in enclosing the rods or wire in achamber, and circulating air heated to at least 200 degrees Fahrenheitand maintained at substantially constant chamber.

2. The method of treating rods and wire to remove brittleness caused byoccluded hydrogen which consists in enclosing the rods or wire in achamber, and causing a heated above 212 degrees Fahrenheit through thechamber.

3. The method of treating rods and wire to remove brittleness caused byoccluded hydrogen which consists in enclosing chamber, recirculating airin said chamber, and passing said air over a heater during its recircutotemperatures above 212 degrees Fahrenheit and maintain it atapproximately said temperatures.

4. The method of treating rods and wire that have been previouslyimmersed in an acid bath to remove scale and then immersed in a limebath to form a lime coating thereon, which consists in enclosing therods or wire in a chamber causing a forced circulation of the air insaid chamber, passing said air during its circulation over a heater toheat said air to at 1621513 200 degrees Fahrenheit and maintaining saidair at said temperature so as to bake said rods to remove occludedhydrogen absorbed from the acid bath and also to dry the lime coatingresulting from the lime bath.

5. The method of treating rods and wire that have been previouslyimmersed in an acid bath to remove scale and then immersed in a limebath to form a lime coating thereon, which consists in enclosing therods or wire in a chamber, causing a forced circulation of the air insaid chamber, passing said air during its circulation over a heater toheat said air to a temperature above 212 degrees Fahrenheit andmaintaining said temperature substantially constant soas to bake saidrods to remove occluded hydrogen absorbed from the acid bath and also todry the lime coating resulting from the lime bath.

ROBERT E. CRAMER.

temperature through the forced circulation of air the rods or wire in a

